1. Field of the Present Invention
The present invention relates to a power supply device.
Priority is claimed on Japanese Patent Application No. 2011-099978, filed Apr. 27, 2011, the content of which is incorporated herein by reference.
2. Description of Related Art
All patents, patent applications, patent publications, scientific articles, and the like, which will hereinafter be cited or identified in the present application, will hereby be incorporated by reference in their entirety in order to describe more fully the state of the art to which the present invention pertains.
For example, a power supply device that includes a plurality of batteries connected in parallel has been known. In the power supply device, positive-side main relays are connected in series between an electric load connected to the power supply device and positive electrode-side terminals of the respective batteries, negative-side main relays are connected in series between the electric load and negative electrode-side terminals of the respective batteries, and precharge circuits where resistors and relays for precharge are connected in series are connected in parallel with the positive-side main relays (for example, see Japanese Unexamined Patent Application, First Publication No. 2008-35581).
In the power supply device, the positive-side main relays are opened and the relays of the precharge circuits are connected for the purpose of preventing excessive current flowing to the electric load. Accordingly, current flows through the resistors of the precharge circuits.
Further, for example, an electric storage device that includes a plurality of batteries connected in parallel has been known. In the electric storage device, resistive elements for eliminating the variation of voltage between the plurality of batteries are connected in series between an electric load connected to the electric storage device and positive electrode-side terminals of the batteries, and resistor short-circuit switches are connected in parallel with the resistive elements (for example, see Japanese Unexamined Patent Application, First Publication No. 2009-212020).
In the electric storage device, the resistor short-circuit switches are turned off and the plurality of batteries are connected to each other by the resistive elements for the purpose of eliminating the variation of voltage between the plurality of batteries. Accordingly, current flows through the resistive elements between the plurality of batteries.
Meanwhile, according to the power supply device in the related art, as the number of the batteries connected in parallel is increased, the number of the precharge circuits is also increased. For this reason, the costs required to form the power supply device are increased and the mountability of the power supply device deteriorates due to the increase in the size of the power supply device.
For example, when relays are connected between junctions of the plurality of batteries and a load, it is possible to reduce the number of required relays. However, the current capacities of the relays need to be increased and the costs required to form the power supply device are increased.
Further, if the resistive elements are provided only in order to eliminate the variation of voltage between the plurality of batteries as in the electric storage device in the related art, the costs required to form the device are increased.